Telephone system.



'b1-R.- 001mm. TELEPHONE SYSTEM. APPLICATION FILED OUT. 12, 190B. RENEWBD MAYV28. 1913.

1,085,974. .Patented Feb.3,1914.;

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||||1|IIIIIIIiIIIIIIIIP-{llhil UMTED strains rati-ENT onirica ELMER R. CORWIIT, OF CHICAGO, ILLINOIS,IA SS;IGNR'TQ CQBWIN TELEPHONE MANUFACTURING COMPANY, OF QI-IICAQQ, ILLINOIS, A QQRPORATION OF ILLINOIS.

TELEPHONE SYSTEM.

Specification of Letters Patent.

APatented Feb. 3,1914..

Application nea october i-aisios, seria1iro.a57,1ee renewed nay es, isis. semi No. 770,491.

To all whom tm/dy concern.' i y Be it known that I, ELMER R. 'CORWIN,

citizen of the United States, residing ,atv

Chicago, inthe county of Cook and State of Illinois, have invented' a cer-tain new and.

" had to the accoiupanyiiw drawings, forming a part-,of this speciticatitdn. v

change systems and has lfor abroad object the provision of means whereby telephonically connected stations of calling and. called lines may, independently-of. each other,=r`e

sume control of their connection initiating line equipment at the exchange or exchanges to. which these linesiextend toenable either lstat-ion fto initiate a new connection While engagement is st'ill maintained between con, tacts of its line and of the link connector' which is employed to connect the lines.

IVhen `the invention is embodied ina manual switch board system it affords means whereby a subscriber.afterurestoring his receiver upon finishing conversation, is

in control of is line indicatorirrespective of the conditionof use of the cord-connecting apparatus, whereby the operatorin attendance upon his calhvwill respondthereto,l

rather thanthe operatorwho took Apart in establishing the existing connection. As --a concrete example, let it beassumed that a subscriber after .having been ,called and`having finished conversation with the subscriber calling him, desires to becomea calling subscriber. In order to do so, the said called subscriber who has becomel the calling subscriber, restores his receiver to his switchhook, whereby through the means of my invention, such called subscriber is thrown out of further control of,V his supervisor signal forming a part of the connection t at said called .subscriber previously had, and whereby said called subscriber is placed iii-control of his line signaling apparatus wliich'the'u his incoming calls' such operator. being in a no longer remains under vthe control of the -cord circuit employed in establishing the.

previously existing connectionl In this way a subscriber who is through with a connection, is enabled at once to signal" the operator who has been assigned to attend to position to serve his wants rather than the operator (assuming her to .be situated at another .positionof the switch-board) who had presidedforer or took -part in establishing-the original connection.

By means of my-invention, the operators that have been selected according `to their capacity to attend tothe trafic of' the exchange,.do not attendito any incoming calls exeeptthose.l that initiate iii line signals, it

' beingv understood th-atwith the system of My invention relates to -telephone ex' my invention neighboring operators may assist eachother" in respo'ndingztoline signals,

-as is at lpresent the practice.

telephoniclapparatus andthe-.ringing generator with cord circuits and the provision of an improved testing circuit arrangement.

The vvarious features and advantages of my invention will .more vfully appear by a description 'of thepreferred :embodiment thereof, fshown in the accompanying-drawing, that illustrates one type of a multiple switch-.board telephone exchange system to which Vmy invention may y be adapted, .but to which type'o'f multiple switchboard system I donot wish-to be lim-ited.

:I have 'shown at A B ltwo telephone substations each including a'ireceiver a, a'transmitter Zr, a switch-hook c, a call bell and acondenser f, the-elements a b c being in-` eluded, in bridge of the telephone line, which lbridge yis open when the receiver is upon theswitch-hook c and which bridge is closed by the-swvitehhook when relieved of L9.04

vthe weight v.offthe receiver. The elemente` ,e f are included in'another bridge fperinaf' nently continuous 4with respect tolalternating signaling vcurrents -but non-continuous with respectto direct currents. The type of sub-stationoutfitshown is one that I have 'selectedffor the purpose of illustrating the vious asthe descriptionof the invention is proceeded with, that the operation of the system does not depend upon the peculiar sub-stationoutit shown. The stations A lB are'connected to the exchange, in the form .of the invention shown, `by means ofmel tallic circuits whose limbs g and. Zi are connected Withl'ine springs ortalkingicontacts of spring jacks g1 Ztl. A plurality lof spring contact of an armature switch, whichswitch is governed in its position by the cut-oft' relay or magnet z, the limbs of each telephone line being normally connected by ,way

of said armature switch and the Contact normally engagedthereby, with a line lamp or signal la and a battery icl adapted to excite said lamp when the circuit including the battery 7h11, the line signal k, the arma' l ture switch of the assoc'iate cutfoif relay z' and the line limbs g and Z1', is closed bythe removal of the telephone receiver at a call ing station from 'its supporting switch-hook. The limbs gland of each telephone line are shown as being grounded,ltaps for the purpose beingcontinued -from the limbs after their connections with the jacks have been passed, which taps are grounded and which include the elements la k1 named. Iny

order to prevent the leakage of voice currentshthe grounded tap of 4each line in permanent-connection with the battery k1 (the battery c1 may be common to a'group of lines, as is well understood) has a retardation coil 7a2 included therein. The cord circuitillustrated includes an' answering lplug Z and a connecting plug Z1 whose tips andsleeves are united by tip and sleeve talking strands and whose body. portions Z2 are adapted for engagement with ,the thimbles of the answering andline multiple jacks. s

Assuming that a subscriber, say subscriber A, has initiated a call by removing his telephone receiver from its switch-hook, and

thereby closing -the circuit through the line signal device Za, the operator in response to' the signal conveyed by the device 7c will insert the answering plugvZ into the jack (in this case the answering jack h1) corresponding to the calling subscriber, whereupon circuit is established through the calling subscribers cut-off relay or magnet 'i (thereby to cut out the signal device by the operation of the cutoff relay z'), which said circuit maybe traced from the grounded terminal of said cut-off relay, through thethimble of the answering ack Ztl, the body portion Z2 of the answering plug, the leftl' hand armature switch of the relay'ml (which relay is brought into service in order t0 place the callin subscriber in control of his line signal a i'shed ,with a connection, all as will hereinafter be set forth), the armature switch and normal contact of the relay n (which relay is employed to convey to the subscriber a -busy test signal, as will appear), the lower winding of the differential relay o, to the r said subscriber has in- A battery p. U on this inclusion of one winding of the di erential relay o in circuit, the

three armature switches shown in associa-A tion with this differential relay are attracted, the tw'o upper armature switches 01 bridging the operators telephone outfit 02 across the talking strands of the cord circuit, the lower armature switch 03 connecting the battery p as a talking battery in a local circuit including the operators transmitter o4. During this stage of the opera-l tion of the system, the calling subscribers supervisory relay g is energized, owing to the closure of the circuit therefor at the' lay g owing to the separatedrelation of the contacts of the lowermost armature switch of said supervisory relay. The circuit for 'the supervisory relay, established by the closure ofthe calling subscribers. switchhook, may be traced from the grounded battery icl, the limbs and sub-station outfit of the calling subscribers line, the sleeve line spring 'of thefjack' engaged by the answering plug, the sleeve contact of the answering plug, the supervisory relay g, to the grounded armature switch of theA relay m by Way of its normal-contact. The operators telephone outt 02 having been connected in bridge of the cord circuit by the inclusion in *circuit of the lowermost wind.

ing of the-differential relay o in the manner that-has been specified, the operator is in position to learn of the wants of the 'calling' subscriber. ample, that the calling subscriber desires connection with subscriber B, the operator takes the testing plug, which may be the connecting plug Z1v that is the mate of the Ascertaining', for eX-- answering plug Z, and touches its tip to the c /testing thimble of a line jack of theicalled subscriber. If the line'happens to be busy, grounded battery p will lbe connectedwith the thimbles of all of the jacks ofthe called line by way of thel connections illustrated1 including the body Z2 o f a plug inserted into one of said jacks. If the called line is idle, `the thimbles of the jacks thereof are not connectedr with the battery p. If battery be connected withcthe tliimble ofl av tested jack, the test circuit established maybe traced from the grounded battery p to the thimble of the tested jack, the appliedftip of the testing plug, the uppermost armaturel casioning the vibration ofthe'relay s to intor with a visual test signal s1 that may be common to the cords at her position, and circuit through which may be traced from the groundedbattery'p to the left-hand armature switch o f relay s, to the grounded signal lamp s1 by way of the front contact of said armature switch. In order that thei p calling subscriber may be .satisfied that the party desired is already in use of his telephone line, I provide abusy back system, which includes, in the embodiment of the yinvention shown, alocal circuit s2 that includes a primary coil s3 upon whichintermittent or alternating current is suitably impressed, the secondary coil s4 terminating in the contacts of the upper armature switches of therelay n. The relay n is energized each time the test relays is energized, `through a circuit which may be traced from the grounded armature switchl of the relay s, Vthe alternate contact of said switch,

the lower armature switch ofrelay r and its contact, the winding of relay 11 to the grounded battery p. Each time the relay n is energized', the secondary s4 is connected acrossthe talking strands of the cord cir' cuit, so that the receiver of the calling subscriber is operated to indicate that the wanted line is busy. Assuming that there is no battery maintained upon the thimbles of the jacks of a called line. (which is thecase when the called line is idle), the relay s will occasion or cause no signal, whereupon the operator will insert the vanswering plug into fthe tested jack. Upon the insertion of theconnecting plug, the operators telephone "set is immediately cut out of circuit and the talking battery pis removed from her trans- -mitter ofby reason of the circuit established through the upper coil of` the dilferential magnet 0,' which counteracts the 'magnetization of the lower coil, allowing the armature switches 'o1 o3 of the relay to fall back. The circuit that is established for the purpose of cutting out the operato-rs telephone outfit Amay be traced from the grounded cut-oli' relay vl of the called line, the thimble of the line jack of the called line engaged by the. connecting'plug, thebody Z2 of such-plug engaging said thimble, the armature switch of relay n, together with its normal contact, the'upper winding of the differential relay o, to the grounded battery p. Circuit is also closed through the relay. a" whose upper armature switches are attracted to close the openings Ain the talking strands thereat and whose lowerarmature switch isattracted to preventoperation of the relay oz.

Before describing the manner in which the ringing f current is impressed upon the called subscribers line, I will slightly describe `the ringingoutfit illustrated, vwhich .terminals 01, which are borne upon by brushes that are connected with the normal contacts of the two upper armature switches Aof the relay lw, said armature switches when in their normal unattracted positions, permitting calling current to be'impressed upon the talking strands, such calling current being conveyed to the line when the relay ris energized, to have its upper armature switches closethe breaks in Athe ltalking strands, as has been described. In order that the signal device or bell e at the calledstation may be rung intermittently,.I periodically interrupt the ringing current impressed upon the upper armature switches of the relay lw by means of the upper' armature switches of vthe relay t1, which, together with their normalcontacts, are 'in serial relation with they upperjarmature switches of the relay w. The relay t1 'is for the purpose intermittently energized through a circuit which may be traced from the grounded battery'p to the brushes which bear upon a rotating collar a1 -',1r'iadeof segments of metal and insulating material connecting said brushes and electricallyseparating said brushes, thence to the lower coil ofthe relay t1, the lowerarmature vmal contact, vthe body l2 of the connecting plug, 'to the called subscribers line.

'relay t1 is alternately energized and de- Venergized, whereby theA .armatureswitohes of said relay t1 are intermittently operated ductors that convey signaling current from the calling generator terminals v1 to -the connecting end of the cord circuit which called subscribers station over the called subscribersline `Prior-to the response of the vcalled subscriber, his clearing-out signal device or lampt'is included in a circuit which may be traced from the-grounded battery p, through said lamp, to the lower armature switch of the relay t1, the armature switchof relay u and its normal contact,

called subscribers cut-off relay z'. When the called subscriber responds, .the upper coil of the magnet fw -is included in a circuit which may be traced from the grounded terminal' of said coil, through the upper coil of the relay. t1, the armature switch of said relay t1 (shown next the core thereof),l the called subscribers portion of the sleeve talking 'strand of the cord circuit, the engaged sleeve for the purpose of alternately electrically switch of relay w, ,which is to be energized?, the armature switch of relay u and its'nor-Av conveys signaling'current to the b ell at the l the body Z2 of the connecting plug, to the impresses ringing current upon the slip ring lOf groundedv cut-off relay z' of the As the composite collar l-.rotates, the lower winding of the to intermittently open and close the conmature switches` away from their normal or l i generator contacts, whereby the generator is automatically removed from circuit with the called subscribers line, the lowermost armature switch of said relay wbeing also at tracted to open the interrupter circuit that includes the lowermost coil of -the relay t1, whereby the armature switches of said relay t1 are no longer. vibrated, the upper winding of the 'relay t1 being in the circuit" that 'was traced through the upper winding of the relay (w, whose' armature switch is atlcircuitis established through the relay u,

tracted, whereby the openings in the cord circuit strands. at the upper armature switches are closed, the circuit of the called subscribers supervisory signal t being at the same time opened at the lowermost armature switch of the relay t1, which thus per-V forms the v'functions 'of a supervisory relay'. Vhen the lowermost switch of the relay w is attracted, it moves against an alternate Contact that constitutes the 'terminal of the lower winding of said relay, which is thereupon included in a local circuit thatis maintainedas long as the connecting plug is inserted within the called subscribers jack,

y and which local circuit may be traced from the grounded battery 10, to the lowerrnost winding of. the relay w, thence to the lowermost armature switch, the armature switch of relay ufthe normal 'contact of relay u,

' the body Z2 and the grounded thimble of the called subscribers jack, it'beingunderstood that, the resistance of the cut-off 4relays z' are low as compared.' y,with the resistance offthe upper winding of relay 0,- for eX- aniple, the resistance of the relays z' being ten .ohms and that of the said winding of relay o'being five hundred ohms. A locking circuit is thus established for the relay w that will prevent the re-application of signaling current to'the line when the called of theupper winding of the relay t1 depends.

subscriber restores his telephone and which will preventthe energization of the relay t1., owing to the opening of the circuit of the lower .coil of the relay t1 at the lowermost armature switch of the relay w. When the subscribers have finished conversation, they restore their telephones to their switch hooks, and inasmuch as I have just been describing the operation of the called subyscribers apparatus, I will describe in detail the operation of the called subscribers supervisory signal that then ensues and the operation of the associate apparatus.

As has been'explained, the-energization upon the circuit that has been traced from the grounded terminal of the upper winding vof the relay fw, through the upper winding l is thus restored yto normal.

of the relay t1, Athrough the limbz of the called line, to grounded battery k1. circuit is broken'when the called subscriber restores his telephone, inasmuch as the condenser f does not aiford a Continous path for the current from the battery icl.

This

The

circuit through the upper winding of the Z1. VUponthe denergizationof the relay t1,

which may beitraced from the grounded coil of said relay, the alternate contact of the uppermost s'witch of the relay lw now engaged by said switch, the normal contact of the uppermost switch of relay t1 now engaged by said switch, the alternate contact` of the uppermost switch of relay r, to the tip of the connecting plug, thence to the grounded battery cl. The relay u, upon its energization, removes the ground from the armature switch of said relay connected therewith by way of the normal' contact of said relay, the body of the callingplug and the cut-off relay of the vcalled subscriber,

'.Q'Iound, however, being restablished in con iiectionv with the armature switch of said relay upon the attraction of said armature switch, whereby the lower coil of'therelay fw is still maintained in circuit, as must be apparent in. view. of the fact that the new ground upon the armature switch of relay a performs the functions of the ground previouslyplaced upon said armature switch, by way of the bodvv of the connecting plug. The l'circuit of the cut-off relay z' of the called subscriber is therefore opened at the normal contact of the armature switch of relay so that said called subscriber after having once'restored his receiver, is placed in full contrjol of his line lamp lo, so that he vmay signal his own operator, in order that he may at alltimes be assured of her service. In this way if the called subscriber desires to be connected with another subscriber immediately after having concluded 'his previous conversation, he may place himself in direct relation with his own operator, to the end that she may attend to his wants. When the operator withdraws the-calling or connecting plug in response to the signal revealedat t, she opens the circuit for the relay u by separating the t1p of the connecting plug Z1 from th'e'spring engaged thereby, whereupon ground is removed from p the'clearing-out or supervisory signal t that vThe ground that was employed to lock the relayw is also calling subscriber withl whom she initiallyl established connection. Inasmuch asthe operator .does not withdraw the plugs unit-v ing lines in conversation u ntil bot-h supervisory signals q1 t are presented,.bothwind ings of the neutral or differential. relay 0 are energizedv, s'o that when the calling subscribers supervlsory relay g 1s denergized upon the re-location of the calling sub- -scribers receiver upon its switch-hook, the

relay m is energized through avcircuit which may be traced from the grounded battery k1 to the tip of the answering plug Z,'the normal contact of the uppermost switch of the supervisory relay g, the winding of the relay m, the adjacent lower armature' switch of the saidsupervisory relay g and its normal contact, to ground by way of the armature switch 03 and its normal contact. When the armature switches of the supervisory relay g' are released (which, as has been stated, is due to the opening of the'circuit therefor at the `calling -subscribers station), circuit is established for the calling subscribers supervisory signal g1, which may be traced from the grounded batteryp, through the supervisory signal device g1, the lowermost armature switch of the relay y and its contact, thence to the left-hand armature switch of the relay my, to the grounded alternate contact of said armature switch. By the movementof the left-hand armature switch oflthe relay m, which is occasioned by the energization o-f the relay m, ground is removed from-the calling subsoribers cutotl' relay z', so that the calling subscribers line signal Z", is again placed withinthe e011-,

trol of said subscriber, whereby the subscriber does no-t have to wait until the answering-plug is withdrawn from his Aanswering jack before he can secure the operation of /his line indicator. In this' way the calling subscriber is sure of getting the services of his own operator, and does not run the chance of securing the services of an operator at distant sections of the board.

When the connection is taken down, the circuit through the magnet m is opened by the disengagement of the tip of the plug Zfrom the tip line spring of the answering ack h1,-

so that said relay fm, is denergized and the supervisory indicator Q1 is restored to normal, as is the case with the other associate parts of the cord circuit apparatus.

Having described the general features of my invention, I will now describe some details, description of which having hitherto been omitted'for t e` sake of clearness. 1

It will be underst od that when the r'e-A lays m and u a1`e energized,tlley remove the testing battery p. fromconnec'tion with the thimbles of the jacks, so that' when said Y lines are tested they will test free, though the plugs Z, Z1 may st-ill be within the jacks.

It goeswithut saying that the batteries p maybe merged into a v'single battery, and take Ipart not only in supplying the cperators telephone outfit with straight current, but also may be employed t'o supply the connect-v ed transmitters of subscribers stations with straight current. If the' called subscriber has lnot restored his telephone, the operator may be thrown into communication with him upon the removal'of the' plug Z, owing to the energization of but one "coil, the upper coil, of the relay o.

Referring back` to the operation of theA composite collar w1, I would pointentv that it serves the importantf1`1n``2t-i`o'n of causing an intermittent operation of the called sub'- scribers supervisory signal t during ythe time that the ringing current is being impressed upon'the called subscribers line,

whether or not the called subscriber is still being called or whether, having been called,

he has finished vwith the connection, for in the latter cas the signal device it would preserve but one set display condition. A third function of theV supervisory signal device is, of course, to indicate to the operator that the called subscriber has responded. y

Attention should be particularly directed to another feature vof my'inventi'on which, in one embodiment, resides in the apparatus illustrated, ywhereby after a subscriber has restored his telephone to it's switchhook, his supervisory signal is as a consequence removed from his control, so that it assumes a set display condition.

It will be seen that I have-provided a telephone system including telephone lines eX-' tending to an exchange from-sub-stations,l jackswitches in association with the tele-- phone lines,'connecting plugs for engagement with said switches, a source of signaling current for operating the signal receivers at called sub-stations and in normal connection with a section of the plug circuit,

which said section is normally disconnected from the answering and connecting ends of the plug circuit, and relay mechanism serving to control the connection of saidfsection of the plug circuit with the `answering and connecting ends of said' plug circuit and to remove the calling generator from .its nor-' mal association with said section of the plug circuit.

Cross reference is made to my co-pending application Serial No.' 639,203,tiledJuly 18, 1911, originally tiled October 12, 1908 under lio serai No. 457,197 and in which some feadisclosed.

tures that are herein disclosed are an exchangeyline signaling apparatus at the exchange for said telephone lines, connecting apparatus at the exchange for uniting lines in conversation, a cut-oftl relay gov` erned by saidv connecting apparatus for preventing the presentation of the line signal of a called line or a calling line, as the case may be, and `electro-magnetic mechanism operable by the apparatus at the called station or calling station, as the case may be,

independently of the apparatus of the call? ing station or called station, as the case may be, for removing the control of the cut-off relay from the line signal of the calledline or calling line, as the case maybe, thereby permitting the called station or calling station,`as .the case may be, to have con-trol of the -line signal of the called line or calling line, as the case may be. v

Having thus described my invention, I claim as new and desire to secure by Letters Patent the following f l. A telephone exchange system including telephone lines extending from sub-stations to an exchange, line signaling apparatus at the exchange for said telephone lines, connecting apparatus at the exchange for uniting lines .in conversation, means governed by said connecting apparatus for effacing the line signalof a calling line, and means,

operating independently of the apparatus l at thecalled station andjointly controlled by the connecting apparatus, when it is employed in establishing a connection, and the sub-station apparatus ofthe calling line for restoring to the sub-station of the calling line its control of its associate line signal apparatus during an established connection.

2. A telephone exchange system including telephone lines extending from substations to an exchange, line signaling apparatus at the exchange for said telephone lines, connecting apparatus at the exchange for uniting lines in conversation, `means governed by said connecting apparatus for 4prevent.- ing the presentation of the linesignal of a vcalled line, and means operating independently of the apparatus at the calling station and jointly controlled by the connecting apparatus, when it is employed in establishing a connection, and the sub-station appasub-station of the called line its control of its associate line signal apparatus during an established connection. b

3. A multiple switch-board system having atest system which includes test thim'bles or contacts of jacks, ytesting terminals of plugs applied to said jack contacts before the plugs are plugged into the jacks, a test circuit. includingl jack test contacts, contacts of plugs plugged intosaid jacks. and engaging the test contacts thereof, the testing terminal ofv an applied testing plg and a suitafble source ofl testing current, means whereby a. completed test circuit is caused to convey a. busy signal to a calling substation, said means including a relay for connecting test busy current A1n association with a calling telephone'line, and a relay i the test circuit/for effecting the operada suitable source of testing current, means whereby a complete-d test circuit is caused to convey a busy signal to a calling sub-station, said means including a relay for connecting test busy current in association with va calling telephone line, a relayin the test circuit for'efiecting fthe operation of the aforesaid relay, and means under the control of the calling line station for dissociating the busy test system from the calling line.

5. A telephone exchange system including telephonelines extending from sub-stations to an exchange, line signaling apparatustat theexchange for said Vtelephone lines, connecting apparatus at the exchange for uniting lines in conversation, a cut-off relay governed by said connecting apparatus, for preventing the presentation of the line signal of a called line, and means, operable by the called party independently of the apparatus of the calling station, for re moving the control of the cut-off relay over the line signal of the called line, thereby permitting the called station to have control of the line signal ofthe called line.

6. A telephone exchange system including telephone lines extendingfrom sub-stations to an exchange, line signaling apparatus at i preventing the presentation of the line sig-v .nal of a called line, and electro-magnetic telephone lines extending from sub-stations to an exchange, line signaling apparatus at the exchange for said'telephone lines, connecting apparatus at theexchange for uniting lines in conversation, abut-oli'l relay governedby said connecting apparatus, for

preventing the presentation ofthe -line signal of a call-ing line, and means, operable by the calling party independentlyot the' apparatus of the called station, for removing the control of the cut-off relay over the line signal of the calling line, thereby permitting the calling station tohave control ofthe line signal of the calling line.

8. A telephone exchange system including telephone lines'extending from sub-stations to an exchange, line signaling apparatus at the exchange forsaid telephone lines, con'- necting apparatus at the' exchange for uniting lines in conversation, a cut-oli. relay governed by said connecting apparatus, for preventing the presentation of theline signal of a calling line, and electro-magnetic mechanism, operable by the'callingparty independently of the apparatus of the called station, for removing the control of the .cuto relay over the line signal of the calling line, thereby permitting the calling station to have control 'of the line signal of the calling line.

9.'A multiple switch-board telephone systeni including telephonically connected sub-' stations and means whereby apparatus of one connected sub-station may dissociate the test system of the switch-board from the line leading tothe said sub-station independently of the apparatus at the other sub-station.

10. A multiple switch-board telephone system including telephonically connected sub-stations and means whereby apparatus of one connected sub-station may dissociate the test system of the switch-board :trom the line leading to said sub-station independently of the apparatus at the other sub-station, said means preventing reassociation of said test system with said line. during an established connection.

11. A multiple switch-board telephone system including telephonically connected sub stations and electromagnetic means individual to a connecting apparatus, whereby apparatus of one connected sub-station may dissociate the test system of the switchboard from the line leading to said substation independently of the apparatus at the v other sub-station.

' 1Q. A multiple switch-board telephone systemincluding telephonically connected 'sub-stations and electro-magnetic means individual to a. connecting apparatus, whereby apparatus of one connected sub-station may dissociate the testsystem of theY switchboard from. the line leading to said sub-station independently of the apparatus at the other sub-station, said means preventing reassociation of said test system with said line during an established connection.

A multiple switch-board :telephone system including telephonically connected sub-stations, a test system, and means operable at one sub-station during an established connection for enabling a line to test idle during an established connection independently of the apparatus at' the other subst ation.

14. A multiple switch-board -telephone system including telephonically' connected substations, a test system, and means oper- .able at one substation during 'connection of 15. A multiple switch-board telephone.

system including telephonically connected sub-stations, a test system, independent of lineJ circuits, and means operableat one substation during aiiestablished connection for enabling a line to test idle during an estab` lished connection independently of the apparatus at the other substation.

- 16. A multiple switch-board telephone system including telephonically connected sub-stations, a test system, independent oit'l line circuits, and means operable at one substation during connection of line-connecting apparatus therewith for Venabling a line to .test idle during connection of line connectingv apparatus therewith independently of the apparatus at the other sub-station.

17. A multiple switch-board telephone system having telephonically connected substations and a test system independent of- -l1ne circuits and including means whereby apparatus of one connected sub-station may dissociate the test system of the switchboard from the line leading to said sub-station independently of the apparatus at the other sub-station.

18. VA multiple switch-board telephone system having telephonically connected substations and a test system independent of line circuits and including inea-ns whereby apparatus of one connected sub-station may dissociate the test system of the switchboard from the line leading to said sub-station independently of' the apparatus at the other `sub-station, said means preventing reassociation of said test system with4 said line during an established connection.

19. A multiple' switch-board telephone istv system having telephonically connected substations-and a test. system independent rof line circuits and including electro-magnetic means individual to a connecting apparatus, whereby apparatus of one connected substation may dissociate ythe test system of the switch-board from the line leading to said sub-station independently of the apparatus at. the other sub-station.l

2d- A ymultiple switch-boardi telephone.

sygsteinhaving telephonically connected substations and 'a test system independent of lline circuits and'including electro-magnetic tions; a link connector joining said lines and means individual-,to aconnecting apparatus,

whereby apparatus vot one connected substation may' dissociate the test system of the switch-board from the line leading to said sub-station, independently of the apparatus at the other sub-station, said means preventing re-associati-on .of said test system with said line during an established connection.;

21. A telephone exchange system including calling andv called telephone lines, the calling line being provided with line equipment at an exchange for initiating connectheir stations in telephonie connection;v means operatingby way of the link connecf tor for preventing operation of Asaid line equipment of the calling line; and means within the control of the calling station and opera-ting independently of the called st'ation for breaking the link connector between the aforesaid means and said line equipment to restore said line equipment to the control of the calling station while calling line and link vconnector contacts are in engagement.

22. A telephone exchange system including calling and called telephone lines,the called line being provided with'line equipment at an exchange for initiating connections; a link connector joining said lines and their stations in telephonie connection;

I vmeans operating'by way of the link connector for preventing operation of said. line equipment-ofthecalled line; and means Within .d the control of thev called station operating independentlyvof the calling stav tion for breaking the link connector between the aforesaid means and said line equipment to restore said line equipment to the control of the called st Bionwhile called line and link connector contacts are in engagement.

28. A telephone exchange system including calling and called telephone lines, each of saidlines being provided with exchange line equipment `for initiating'connections; a link connector joining said lines and their stations in telephonie connection means operating by way' of the link connector for preventing operationv of the line equipment of the calling and called lines; and means at each of the stations operating independently of the" other station for breaking ,the link connectorbetween the aforesaid means and its Loenen line equipment to restore the corresponding line equipment to the control of its station while link connector contacts are in engagement with calling and called line contacts. 24. A. telephoneexchange system includ- Ying calling land called telephone lines, the

calling line being provided with line equip'-` inent at an exchange for initiating connections a link connector joining said lines and their stations in telephonie connection and having' operator controlled means for con- 25. A telephone exchange system including calling and called telephone lines, the called line being provided with line equipment `atjan exchange for initiating connections;

a link connector joining said lines and their stations. in telephonic connection and having operator controlled mea-ns for connecting it wit-h the called line; means operating by Way of the link connector for 'preventing operation. ot' said line equipment of the called line; and means within the control of the called station operating independently of the calling station for. breaking thelink connector between the aforesaid means and .said line equi ment to restore said'line equipment to t ejcon'trol ofthe called station while called line 'and Vlink connector contactsare in engagement.

26. Atelephone exchange system including calling and called telephone lines, each of'said lines being provided with exchange line equipment 4for initiating connections; a link connector joining said Vlines and their "stations in telephonie connection and having operator controlled means i'or connecting it with the 4calling and called lines; means operating by rWayof the link-connector for preventing operation of the line equipment of the calling and called lines; and means at each lof the stations operating independently of kthe other stations for breakingy the linkv connector between the aforesaid means and vits line equipment to restore the corresponding line equipment to the control of its station, while link connector 'contacts arein engagement With calling and called line contacts.

27. A telephone exchange' system including calling and called v telephone lines, the calling line being provided with line equipment at an exchange for initiating connections; 'a link connector joining said lines and their stations in telephonie connection and having operator controlled means for connecting it with the calling line; means for preventing operation of saidline equipment of the calling line during anestablished 'oonnection; and means Within the control of the calling station and operating independently of the called station for removing the influence of the aforesaid means from said line equipment to restore said line equipment to the control of the calling station while calling line and link connector contacts are in engagement.

28. A telephone exchange system includ- .ing calling and called telephone lines, the

called line being provided with line equipment at an exchange for initiating connections; a link connector joining saidlines and their stations in telephonie connection and having operator controlled means for con necting it with the called line; means for.

preventing operation of said line equipment of the called line during an established connection; and means within the control of the called station operating independently of the calling station for removing the influence of the aforesaid means from said line equipment to restore said line equipment to the control of the called station While called line and link connector contacts are in engage' ment. l

29. A telephone exchange system including calling and called telephone lines, each of said lines being provided with exchange' line equipment for initiating connections; a llnk connector Joining sald llnes and their stations 1n telephonic connection and having operator controlled means for connecting it the stations operating independently of the4 other station for removin the influence of the aforesaid means from its line equipment to restore such equipment to the control of its station While link connector contacts are in engagement With calling and called line contacts.

In Witness whereof, I hereunto subscribe my name this 10th day of October A. D., 1908.

vELMER R. QORWIN.

Witnesses:

G. L4 CRAGG, L. G. S'rRoH. 

